In Genshin Impact you can get the Festering Desire sword for free during the Chalk Prince and the Dragon event. You can make this sword stronger by refining it over the course of the event. You can refine it in two stages with two sub-events. These sub-events need to become active over the course of the main event.
You can Refine the Festering Desire to Level in Act 2 of the event, and you will have to do some crushing in the main activity of the Act.
How to Refine The Festering Desire Sword In Genshin Impact
Ley Line Disorders will appear in Dragonspine after Act 2 begins and you have to play through some of these to refine Festering Desire. These Ley Line Disorders will be marked as a red icon on the map.
Go to the marked location and there you will find a shrine in the center interact with it and 8-9 enemies will spawn in, and you will have to kill them all. After you kill them all, a strange stone chest will appear, open the chest and you will get 140 Glimmering Essence.
Farm these until you have 600 Glimmering Essence, Once you get 600 of these Glimmering Essence go to the event shop to buy an item called Festering Dragon Marrow. After buying it go to the character screen then go to the weapons section and then click to enhance the Festering Desire Sword. Then choose to refine and select the Festering Dragon Marrow and your Festering Desire will be refined to level 2.
How to Refine Festering Desire to Level 3
A new activity will become available during Act 3. There are small differences in this activity but it is almost the same as the one to get Glimmering Essence. This time you won’t find any heat totems around the area, instead, you can use a warming Seelie to battle with Sheer Cold. You will get Scart Quartz sometime dropped by the Seelie that you can use to stop Sheer cold or give more damage.
You will get 140 Warm essences from each instance, and same as Glimmering Essence you will need 600 warm Essence to buy Festering Dragon Marrow from the event shop. After that, you can refine the Festering Desire to level 3 by repeating the same process you did for level 2.